Principles of Instrumental Analysis
7th Edition
ISBN: 9781305577213
Author: Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher: Cengage Learning
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Chapter 27, Problem 27.25QAP
Interpretation Introduction
Interpretation:
Percentages of each component should be calculated.
Concept introduction:
Area normalization method is used in quantitative analysis of compounds in chromatography. In this method of quantification, complete elution of all analytes in the sample is required. Following formulas are required for the calculation.
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One method for the quantitative determination of the concentration of constituents in a sample analyzed by gas chromatography is area normalization. Here, complete elution of all the sample constituents is necessary. The area of each peak is then measured and corrected for differences in detector response to the different eluates. This correction involves dividing the area by an empirically determined correction factor. The concentration of the analyte is found from the ratio of its corrected area to the total corrected area of all peaks. For a chromatogram containing three peaks, the relative areas were found to be 16.4, 45.2 and 30.2, in order of increasing retention time. Calculate the percentage of each compound if the relative detector responses were 0.60, 0.78 and 0.88, respectively.
The response of the instrument must be lincar in the sample matrix.
Systematic errors can occur due to sample or standard preparation.
It consists of a series of standard analyte solutions separate from the unknown.
A blank is used to correct the response from the instrument.
Known quantities of a standard solution of the analyte are added to the unknown.
It is the method of choice when the matrix of the sample may affect the signal.
Matrix effects can cause the same analyte concentration in an unknown and standard to give different responses.
It is used to measure the instrument response as a function of a known analyte concentration under a set of conditions.
What are the differences between systematic and random errors and how do they effect accuracy and precision?
In what circumstances would you use standard addition (versus a normal calibration curve) to determine the amount of an analyte in a sample?
A urine sample, containing analyte Z is analysed by the standard addition method where 5 mL of the original sample was mixed with increasing amounts of a Z standard and each solution diluted to a volume of 50 mL prior to analysis. A plot of the final concentration of the standard in each of the 50 mL samples (x axis) versus
The measured signal from the analysis of each 50 mL sample (on y axis) produced a straight line with the general equation:
y = 44.72x + 4.06
what was the final concentration of Z in the 50 mL standard addition sample? what was the initial concentration of Z in the original urine sample?
Chapter 27 Solutions
Principles of Instrumental Analysis
Ch. 27 - Prob. 27.1QAPCh. 27 - Prob. 27.2QAPCh. 27 - Prob. 27.3QAPCh. 27 - Prob. 27.4QAPCh. 27 - Prob. 27.5QAPCh. 27 - Prob. 27.6QAPCh. 27 - Prob. 27.7QAPCh. 27 - Prob. 27.8QAPCh. 27 - Prob. 27.9QAPCh. 27 - What are hyphenated GC methods? Briefly describe...
Ch. 27 - Prob. 27.11QAPCh. 27 - Prob. 27.12QAPCh. 27 - Prob. 27.13QAPCh. 27 - Prob. 27.14QAPCh. 27 - Prob. 27.15QAPCh. 27 - Prob. 27.16QAPCh. 27 - Prob. 27.17QAPCh. 27 - Prob. 27.18QAPCh. 27 - Prob. 27.19QAPCh. 27 - The same polar compound is gas chromatographed on...Ch. 27 - Prob. 27.21QAPCh. 27 - Prob. 27.22QAPCh. 27 - Prob. 27.23QAPCh. 27 - Prob. 27.24QAPCh. 27 - Prob. 27.25QAPCh. 27 - Prob. 27.26QAPCh. 27 - Prob. 27.27QAPCh. 27 - Prob. 27.28QAPCh. 27 - Why is GSC not used nearly as extensively as GLC?Ch. 27 - Prob. 27.30QAP
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